Cyanobacteria are classified in the kingdom Monera, division Myxophyta, and class Cyanophyceae. They are commonly known as blue-green algae due to their blue pigmentation. Cyanobacteria are prokaryotes that can live in a variety of habitats including lakes, soils, and hot springs. They reproduce asexually through various methods like hormogones, heterocysts, and akinetes. While similar to bacteria in several structural features, cyanobacteria also share some characteristics with algae like presence of chlorophyll and ability to photosynthesize.

2. Diagram of Cyanobacteria

3. Terminology of Cyanobacteria
Kingdom: Monera
Division: Myxophyta
Class: Cyanophyceae
Cyanobacteria known botanically as
cyanophyta or blue-Green algae.

4. •The name Cyanophyta has recently been adopted for
this division.
•The Division was named Myxophyta (Gr.
Myxa=slime+ phyton= a plant.
•Most of the characteristics are similar to that of
bacteria. Therfore they are placed alongwiith kingdom
Monera .
Introduction

5. •However , they are classified nearer to algae
because of presence of chlorophyll –a and
liberation of O2 similar to other algae group.
•They are commonly called blue green algae
because of dormant blue photosynthetic
pigment in their choromatophores.

6. Habitat
 Mostly present in lakes , ponds etc.
 On terrestrial with moist surface.
 Also present in hot springs.
 Few present in a marine.
 Few species are entophytes i.e. live in the cavities of
other plants. For example : Nostoc and Anabaena.

7. Cell Structure
 Unicellular , most are multicellular.
 Trichome with mucilage form the filament.
 Form colonies.
 Plastid absent.
 Defined nucleus absent.
 Endoplasmic reticulum and Golgi bodies are absent.
 DNA aggregate in cytoplasm that is nucleoid.

8. •Phycobilisomes are protein complexes (up to
600 polypeptides)
•Any thin layer of organic tissue can be called
a lamella

9. Reserve food material
 Sugar.
 Glycogen.
 Oil droplets.
 Protoneious material Cyanophycin.
 Anabaena fix nitrogen into nitrates.

10. Reproduction
Cyanobacteria reproduce Asexually
 Hormogones: small parts of filaments detached by direct
breaking of by formation of special disk.
 Heterocyst: Special large cell with thick walled, present in
the filaments and is detached at this point.
 Hormospore: The cells become enlarge and thick walled
.On separation these Hormospore produced new filaments.

11.  Akinetes: Vagetative cell along with the original
cell wall transformed into spores.
 Endospores: Spores produced after the division
of protoplasts.
 No sexual reproduction
Motile reproductive bodies are entirely absent.
There is no sexual reproduction present in the
members of Cyanophyta.

12. Useful
 Role in nitrogen fixation
 Role in soil building
 Prevent soil erosion
 Prevent saline soil
Harmful
 Death of fish
 Death of animal
 Water pollution
 Bad odour

13. Affinities with bacteria
 Cell wall same.
 Slimy sheath same.
 Mucilaginous.
 Nucleus and plasmid absent.
 Asexual reproduction.
 Chlorophyll a, b and certain pigments.
 Nitrogen fixation.

14. Affinities with red algae
 Sheath composition
 Phycocyanin and phycoerathrins
 Cyanophycean starch
 Non motile